Yemen, a US ally, has been in upheaval since a popular uprising ousted veteran president Ali Abdullah Saleh in February. Overlooking one of the world’s busiest oil shipping routes, Yemen is plagued by poverty and lawlessness that the toppling of Saleh has done little to change.

Washington, which has pursued a campaign of assassination by drone and missile against suspected al-Qaida members, backed a military offensive in May to recapture areas of Abyan province – which borders Shabwa province – from Islamist insurgents.

But militants have struck back with a series of bombings and killings. Earlier on Thursday, the Defence Ministry said two bombs went off at the gate of the local council headquarters in Yemen’s southern city of Ma’ala, wounding two soldiers.